Tone arm fok electric phonographs



Inventor: Martin Zeh, b MW His Attofr'le y.

M ZEH TONE ARM FOR ELECTRIC PHONOGRAPHS Original Filed Feb. 17; 19 52Fig! Jan. 18, 1938.

Reissued Jan. 18, 1938 UNITED STATES PATENT OFFICE TONE ARM FOR ELECTRICPHONOGRAPHS Martin Zeh, Friedenau, Berlin, Germany, assignor to GeneralElectric Company, a corporation of New York 4 Claims.

My invention relates to tone-arms for electric phonographs adapted toboth the recording and the reproducing of sound vibrations by means of arecorder and reproducer unit and an amplifier, particularly theamplifier of a radio receiver, the loud-speaker of the radio receiverbeing utilized also as a microphone.

Radio receivers and electric phonographs are known which are so arrangedthat by means of separate switches or by means of a single rotary switchthe apparatus may be connected to produce the following results:

The reproduction of radio programs by means of a loud speaker,

The recording of speech or music on sound discs,

The recording of radio programs on sound discs,

The reproduction of radio programs which have been recorded on sounddiscs,

The amplified reproduction of announcements.

My present invention is directed to a tone-arm for electric. phonographsof such character that it is possible to convert, in a simple manner,existing electric phonographs arranged only for sound reproduction intoapparatus capable of producing the several results above set forth, byproviding the existing phonographs with the tone-arm constructed inaccordance with my invention, the required current conducting andswitching means being simple and reliable in operation. In accordancewith my invention, I provide for the electric phonograph a tone-armresembling the usual tone-arm in appearance but in the interior of whichis mounted a switching device which is adapted, in combination withconductors leading to the loud speaker and to the input circuits of theamplifier, for example the amplifier system of a radio receiver, toconnect theapparatus either for the recording or reproducing of sound asdesired. On the outer wall of the tone-arm is mounted a switchingelement or rotatable knob for manual operation.

The supply conductors for the input and output circuits of the amplifierare preferably connected to amplifier tube sockets already comprised inthe amplifier structure, and to these sockets, in case the amplifyingapparatus of the radio receiver arranged for sound reproduction from aphonograph disc is used, the sockets for the sound box or the loudspeaker correspond. The loudspeaker, which may be used also as amicrophone, or the connecting plug of the loud speaker, is connected inaccordance with the invention to sockets which are themselves connectedto corre- In Germany February 2'7, 1931 spending terminals of theswitching device and are attached either to the phonograph casing or bymeans of a socket or mounting member to the stranded cable whichcontains the conductors leading to the switching device.

Preferably the sound volume adjustment means for the recorder andreproducer unit or sound box, together with necessary elements forcoupling or for adjusting the sound box or the loud speaker, is mountedwithin the tone arm, especially within the head portion thereof. Sucharrangement of parts is preferable not only for constructional reasons,but also because thereby the switching device, the loud-speakerregulator, the

required coupling elements and a considerable portion of the conductorsare electrically shielded. The switching device consists preferably ofone or more groups or sets of springs which may be switched into and outof contact by a handle or knob mounted on the tone-arm.

The weight of the usual sound box intended only for the reproduction ofsound is much too small to cause sufficient pressure of the needle soundthe phonograph plate for the recording of sound, 1. e., for the formingof the sound groove in the record. It is therefore essential to load thesound box during the recording operation. In accordance with myinvention, simultaneously with the setting into operative position ofthe loading device the handle of the electrical switching device, or ofan element connected therewith, is operated.

My invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawing and itsscope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 illustrates diagrammatically a soundreproducing and recording apparatus embodying my invention; Fig. 2 is airagmental sectional view of a tone-arm containing a switching device inaccordance with my invention; Fig. 3 is a cross sectional view of atonearm in accordance with my invention; and Fig. 4 is a partiallydiagrammatic View showing soundbox, switch and amplifier connections ofa sound reproducing and recording system embodying my invention.

Fig. 1 illustrates diagrammatically the change of connection of anelectric phonograph soundbox which for the purpose of reproducing soundis ordinarily connected through an amplifier to a loud-speaker, whichwill enable the sound-box to record sound or similar vibrations. Duringthe reproduction of sound the sound-box must be connected to the inputcircuit of the amplifier and the loud-speaker to the output circuit ofthe amplifier. But, for the purpose of recording sound, theloud-speaker, which then functions as a microphone, must be connected tothe input circuit of the amplifier, and the sound-box, which then servesas a recording tool, to the output circuit of the amplifier.

In Fig. 1 the numeral I represents an amplifier having input terminals 2and output terminals 3, the numeral 4 an electric phonograph sound-box,the numeral 5 a loud speaker, and the numeral Ii an adjustment means bywhich the amplitude of the: impulses impressed on the input of theamplifier I may be varied. In order to couple the sound-box 4 with theinput and output circuits of the amplifier I a condenser 1 is connectedin series with one of the sound-box leads and a choke coil 8 isconnected in parallel to the leads. The numeral 9 represents a switchingdevice by means of which the apparatus may be connected either for therecording or for the reproduction of sound. The switch device 9 is soarranged that the four switch blades Ill bear on the four contacts IIwhen recording sound, and on the four contacts I2 when reproducingsound.

In order to switch from the recording to the reproducing position andvice-versa a jack arrangement maybe used which is adapted to be movedinto the required positions by means of a plug. As shown in Figs. 2 and3 the jack or multiple spring contact device, which consists of twogroups of springs I3, I4 and the plug or spreading pin I5, is mounted inthe interior of the tone-arm IS. The plug I5 is connected through a bentmember I! with a control knob I8 which is adjustable on the tone-arm andmay be moved in the direction of the arrow I9 toward the right or left.The position of the control knob I8 shown in full lines corresponds tothe position of sound recording, and the position indicated by dottedlines to the position of sound reproducing. In the latter position thesprings 20 of the jack are pressed apart by the plug or spreading pin I5and the springs of the groups- I3, I4 are thus moved into the desiredposition for sound reproducing.

Simultaneously with the switching over tothe reproducing position thesound box, represented by the numeral 2 I- in Fig. 3, is loaded by meansof the switching knob I3 operating the bent piece I'I connectedtherewith. For the purpose of loading the tone-arm a spring 22 isfastened thereto, this latter spring, in case the apparatus is connectedfor reproducing sound, assuming the position indicated by dotted linesinFig. 3. In case, however, the apparatus is connected for recordingsound the spring 22 is forced by the bent member I'I into the positionshown in full lines. The spring 22 then exerts apressure upon a pin 23or the like connected with the linking member 24 of the sound-box 2 I.

'In the head 2501 the tone-arm I5 are mounted the choke coil 8, thecondenser I, and the amplitude adjusting means '6 which is adjustable bymeans'of a rotatable knob 25. The-contact springs I3, I4 are connectedto the input circuit of the amplifier, for example by connection to thephonograph terminals of a radio receiver, and tothe output circuit ofthe amplifier, for example by connection to the loud speaker terminalswhen a radio receiver is employed. The connecting of the switchingdevice to the input circuit of the amplifying apparatus is effected bythe two-pin plug 21 and the'connection to the output circuit by the plug28. From plugs 21 and 28 two conductor cables 29 and 33 lead to thesocket member 3 I, which is provided with two plug sockets 32 for theloud-speaker connection cord or cable. From the socket member 3I, whichis preferably mounted on the casing of the phonograph or on the casingof the amplifier or of the radio receiver, a stranded connection cable33 containing the six required conductors leads through the tone arm I6to the elements 6, I, 8, I3 and I4.

The required terminals and conductors are represented schematically inFig. 4. In the latter figure for the sake of clearness the condenser Iand choke coil 8 are not shown. In place of the amplifier I shown inFig. 1, in Fig. 4 a four tube radio receiver 34 is shown comprising ahigh frequency amplifying tube 35, a rectifying tube 36 and two lowfrequency amplifying tubes 31, 38. The terminals 39 represent the outputterminals of the receiver and to these terminals the loud speaker isnormally connected. In the arrangement shown in Fig. 4 the rectifyingtube 36 is employed for amplification in the well known manner for thereproduction either of broadcast programs or of sound from a phonographrecord. The numeral 40 represents the terminals or plug sockets whichare usually provided in such apparatus for the connection of thesoundbox leads. In like apparatus the arrangement is usually such thatwhen the sound-box connections are inserted at 40 the high-frequencyamplifying stage 35 automatically becomes inoperative. In the presentcase, shown in Fig'. 4, the terminals or sockets and 39 are to beregarded respectively as the input and output terminals of theamplifying device, which is indicated by dotted lines, comprising thetubes 36 to 38. Terminals 39 and 40 may be connected with the contactsprings of the jacks I3, I4 in the manner illustrated in Fig. 4,terminals 39 being connected to contact springs M and terminals 40 tosprings 42. The loud-speaker is connected to the sockets 43 whichcorrespond to the sockets 32 shown in Fig. 3, The conductors locatedwithin the tonearm l6 and leading to the winding of the soundbox 2| areconnected at 44 and the conductors leading from the sockets 43 areconnected at 45.

When the contact springs of jacks I3, I4 are in the position shown inFig. 4 the loud speaker is connected with the output circuit of theamplifier and the sound-box with the input circuit of the amplifier.Under these conditions the apparatus is connected for the reproductionof sound records. If, however, the springs 20 are spread apart by meansof the plug or spreading pin I5 the contact springs 44 and 45 are then,through the insulated studs or pins 45, brought into such a positionthat the loud speaker is connected with the input circuit of theamplifier and the sound-box with the output circuit of the amplifier.The apparatus is then connected for the recording of sound vibrations orthe like. In the case of the apparatus shown in Fig. 4 as distinguishedfrom that shown in Figs. 2 and 3 the switching arrangement is such thatthe apparatus is connected for sound recording when the springs 20 arepressed apart, and for the reproduction of sound from records when thesprings are permitted to approach each other.

The switching devices, illustrated herein as jacks I3, I4, may be formedand arranged in many different ways. Instead of the switching ,meansshown herein, or similar switching means,

a suitable rotatable switch may be provided. It is essential, however,that the switching or circuit control means and the tone-arm constitutea unit, whereby an apparatus such as a usual electric phonograph mayproduce the desired results merely by providing the phonograph with thetone-arm unit in accordance with my invention.

It is obvious that the switching or control device combined with thetone-arm may be constructed in such a manner as to perform otherswitching or control operations required for the apparatus. In theembodiment of the inveniion described herein broadcast programs may berecorded on phonograph records merely by withdrawing plug 21 from thecorresponding sockets of the radio receiver and by setting the knob l8in the position for sound recording. The broadcast signal then passesfrom the output circuit 39 of the receiver to the winding of thesound-box 2|.

For many purposes, for example for use of the apparatus as a dictationdevice, it is preferable to provide a special microphone for the recepiion of speech, preferably in such a manner that signals will beimpressed from the microphone upon the input circuit of the amplifier aswell as upon the loud-speaker. The switching or control arrangements ofthe apparatus may be suitably changed and extended for this purpose. Themicrophone may be connected to the apparatus by means of the samemounting which serves for the connection of the loud speaker. A simplerconnection means is provided if the microphone plugs are inserted in theloudspeaker sockets, after the loud-speaker plugs have been withdrawnand the apparatus is con nected for sound recording.

The invention is in general adapted to rendering sound reproducingapparatus readily convertible into sound recording apparatus. Theinvention is especially useful when applied to apparatus by means ofwhich messages, statements, questions, or the like are to be recordedand immediately reproduced at the place of recording or dispatched inphonograph record form by post in place of letters or the like,thereafter to be reproduced by the recipient by means of the combinedradio-phonograph apparatus. The phonograph discs or records employed forthe latter purpose are preferably such that after the sound record ismade the discs are suitable for the reproduction of sound withoutspecial or further treatment.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In electric phonograph apparatus comprising a sound-box, an amplifierand a microphone device, a hollow tone-arm structure, a supporting headfor said tone-arm structure, switch means to connect said apparatus forsound recording or for sound reproduction, and circuit coupling meansassociated with said sound-box and microphone device, said switch meansbeing mounted Within said tone-arm structure and said coupling meansincluding elements mounted within said tone-arm supporting head, wherebyspace otherwise wasted within said hollow tone-arm structure is utilizedfor housing a portion of said phonograph apparatus.

2. In electric phonograph apparatus comprising an amplifier and .amicrophonic device, a hollow tone-arm, switch means to connect saidapparatus for sound recording or for sound reproduction, terminal meansfor said microphone device, conducting means to connect said switchmeans and said terminal means, and conducting means to connect saidterminal means to the output circuit of said amplifier, said switchmeans and a portion of the first-named conducting means being mountedwithin said hollow tonearm whereby space otherwise wasted within saidtone-arm is utilized for housing a portion of said phonograph apparatus.

3. In electric phonograph apparatus comprising a sound-box, an amplifierand a loud speaker, a hollow tone-arm structure, a supporting head forsaid tone-arm structure, switch means to connect said apparatus forsound recording or for sound reproduction, and circuit coupling meansassociated with said sound-box and loud speaker, said switch means beingmounted within said tone-arm structure and said coupling means includingelements mounted within said tone-arm supporting head, whereby spaceotherwise wasted within said tone-arm structure is utilized for housingthat portion of said phonograph apparatus including said switch meansand coupling elements.

4. In electric phonograph apparatus comprising an amplifier and a loudspeaker, a hollow tone-arm, switch means to connect said apparatus forsound recording or for sound reproduction, terminal means for said loudspeaker, conducting means to connect said switch means and said terminalmeans, and conducting means to connect said terminal means to the outputcircuit of said amplifier, said switch means and a portion of thefirst-named conducting means being mounted within said hollow tone-armwhereby space otherwise wasted within said hollow tonearm is utilizedfor housing a portion of said phonograph apparatus.

MARTIN ZEI-I.

